The difficulty curve of the past 6 months shows a slowing down of acceleration to me.
Wishful thinking IMOhttp://bitcoin.sipa.be/speed-lin.png
Next difficulty again +~10%.
And in spite of the mass production of FPGAs, the difficulty hasn't recovered to the level of last August's. So it's a drop over the past 10 months.
If you are going to look at difficulty of last summer, you cant ignore BTC price. But because you invest in BTC and get your return in BTC, any profits (or losses) coming from a BTC rise have to factored out. After all, if thats what you are betting on, you should just buy or sell BTCs. So you really have to look at BTC price / difficulty, and that has been going down fairly steadily:http://bitcoinx.com/charts/chart_large_log.png
Note the log axis. I see no reason why that trend would reverse, quite the opposite.
Buying these mining bonds at current prices only makes sense to me if you assume three things: the declining BTC/difficulty trend willl somehow reverse AND the reward halving will cause a significant drop in difficulty mostly offsetting it AND those (s)-asics will not arrive for another ~12 months. That a lot of assumptions and I would be willing to bet against any of them individually; let alone the combination of them.
Of course, it will even explode more once 20nm ASICs destroys 130, 65, and 45nm ASICs. The problem is when.
Thats actually unlikely to happen, given the extremely low marginal costs of asics, the performance gains from shrinking asics to newer process nodes is unlikely to be big enough to warrant the investment any time soon, if ever; but thats for another discussion. Agreed that the 'when' is a big factor, but (s)asics are the sword of Damocles hanging above your bonds; its not a matter of if it will drop, but when and Id be very surprised if it didnt hit in the next 6-9 monts. Anticipation and resulting value loss of these bonds will begin a lot earlier, probably as soon as a time table is made public.
Besides the reasons I listed above, I have to add another: Imagine the Bitcoin price drops to 1/10 of the current level. If you have 100BTC (600+$) and don't invest in anything now you only 60+$. But if you buy PIMP bonds at 0.25BTC/each, we can safely predict that the difficulty will decrease to at least 1/4 of the current level (hard to pay electricity bills, lots of mining operations closing). Then you have a 28% per month return, which translates to 1934BTC after a year if you reinvest, that is, more than 1160$. Isn't it a good investment if you could turn 60$ to 1160$ in a year?
If you want to speculate on a huge price drop or rise, buy or short bitcoins and you will make a whole lot more if your prediction pans out. A said earlier, those bonds are denominated in BTC and earn you BTC, so thats what you have to look at. Difficulty dropping to 1/4 just aint gonna happen, but if you are willing to make a bet in that direction, Im certainly up for it.